Broken rib

[Bob Turner]

My minor project last week was a fractured and loose rear rib on a 160 GCAA. Apparently it went to a shop for fabric restoration in the slipstream, and they replaced the aft section of the #2 right wing rib with a hand-fabricated part.

First indication was the lower surface tape coming loose. I just assumed it was dope failure, and glued it back. Then the trailing edge broke, and most assumed it had hit something.

What really happened was the pop rivets holding the rear rib to the spar were supposed to engage the fuel tank rib, and they "missed." So, both rib sections were flopping in the slip stream, pulling the rib stitch rivets through both fabric and reinforcing tape. You could see the rear spar flexing!

 

[Hiperbiper]

If the spar is wood the aft repair rib section pn#51855 works great. The flange attaches with nails to the rear face of the aft spar and doesn't depend on the remaining portion of the rib for support.
Chris

 

[Bob Turner]

Thanks. Pop rivets would be even worse on wood spars, I guess. We used three 8-32 screws with small fender washers both sides.

A trick I have taken a long time to learn - one of those small pencil tip soldering iirons goes through the reinforcing tapes without leaving wrinkles or stressing the tapes. Test-flight today.